Ramalina Lichens and Their Major Metabolites as Possible Natural Antioxidant and Antimicrobial Agents

Three lichen species of Ramalina (R.farinacea, R.fastigiata and R.fraxinea) were examined. Evernic, fumarprotocetraric, lecanoric, stictic and usnic acid levels were determined by high performance liquid chromatography-diode array detection. Acetone, methanol and ethanol were used to examine the efficiencies of different solvent systems for the extraction of lichen acids. The total phenol contents in the extracts were determined by the Folin-Ciocalteu method. The antioxidant capacities were determined by the ABTS (2,2-azino-bis[3-ethylbenzothiazoline-6-sulphonic acid]) method. The methanol extracts of the Ramalina species showed the highest antioxidant capacities. Broth microdilution testing was performed to determine the minimum inhibitory concentration (MIC) of the methanol extracts of the three Ramalina species. The MIC values of all extracts ranged from 64 to 512g/mL for all bacterial strains tested in this study